Immaculate Conception School in Celina closed its doors at 10:45 a.m. Friday because half of its student population was absent with flu-like symptoms, according to school Superintendent Kathy Mescher.

Mescher initially canceled only kindergarten classes on Friday after half of the 21 students were absent on Thursday. Most of those children reportedly were experiencing flu symptoms including vomiting, she said.

"We talked to the health department and they agreed it was best to send everyone home," she said. "We have no regrets doing that."

Mescher said the action was necessary to allow ill students to recover during the weekend and prevent the spread of whatever virus is plaguing the school.

The Catholic school educates about 225 students ages preschool to sixth grade. Mescher said she believes this is the first time the entire school has closed for an illness outbreak.

At Mescher's request, local health officials came to the school on Friday to provide support and guidance. As a precaution, they also examined food and preparation methods and found no problems, Mescher said.

None of the students' illnesses were diagnosed as H1N1 - a type of flu that has become widespread across Ohio and the globe. Health departments and physicians all over the U.S. have been instructed by the Centers for Disease Control (CDC) and Prevention to only test patients who are hospitalized with flu symptoms or when mass outbreaks are reported.

It wasn't determined on Friday whether any of the ill students will be tested for the H1N1 virus, which overall produces only minor cases of the flu.

As of Friday, no other school system in the Grand Lake area had reported high absenteeism, according to health department officials in Mercer and Auglaize counties.